1. Field of the Invention
The present invention relates to a sheet feeding apparatus for feeding sheets to a printer, a copier, etc., and an image forming apparatus provided with the sheet feeding apparatus.
2. Related Background Art
In a conventional image forming apparatus such as a printer or a copier, it is required to contain a large number of sheets on each of which an image is formed, along with higher speed operation of the image forming apparatus. However, there is a limit in increasing a capacity for containing sheets because, if a capacity for containing sheets in an image forming apparatus main body is increased, the image forming apparatus main body is enlarged. Thus, an image forming apparatus has been proposed which is provided with a sheet feeding apparatus on a side surface of the image forming apparatus main body other than a sheet cassette mounted in the image forming apparatus main body, thereby realizing increase in a capacity for containing sheets. An example of such an image forming apparatus is described in Japanese Patent Application Laid-Open No. 2001-310829.
FIG. 40 is a perspective view for explaining a sheet feeding apparatus described in Japanese Patent Application Laid-Open No. 2001-310829.
In the figure, reference numeral 900 denotes an image forming apparatus main body which forms an image on a sheet according to, for example, an electrophotographic process, and 901 denotes a sheet feeding apparatus which is disposed on a side surface of the image forming apparatus main body 900. An upper door 940 is constituted so as to open and close around a horizontal shaft 941 provided in the vicinity of the image forming apparatus main body 900 and form an opening on an upper surface side of the sheet feeding apparatus 900, that is, above a sheet mounting stand 910.
First and second upper door detection switches 943 and 944, which detect an opened/closed state of this upper door 940, are attached to an upper edge on a front surface side of the opening formed by this upper door 940. Detected pieces 943a and 944a, which press these two upper door detection switches 943 and 944 when the upper door 940 is closed, are provided on a lower surface of the upper door 940.
A side door 950 is constituted so as to open and close around a vertical shaft 951, which is provided at a side edge on a side opposite to the image forming apparatus main body 900, and form an opening on a side surface side of the sheet feeding apparatus 901 on the opposite side of the image forming apparatus main body 900, that is, besides the sheet mounting stand 910.
In addition, first and second side door detection switches 953 and 954, which detect an opened/closed state of this side door 950, are attached to a side edge on a front surface side on a side surface side of the opening formed by this side door 950. Detected pieces 953a and 954a, which press these two side door detection switches 953 and 954 when the side door 950 is closed, are provided on an inner side surface of the side door 950.
However, as in such a conventional sheet feeding apparatus, if a plurality of sensors such as the upper door detection switches 943 and 944 and the side door detection switches 953 and 954 for detecting an opening and closing of doors are provided in association with the upper door 940 and the side door 950, respectively, costs for the sheet feeding apparatus including an arithmetic controller unit increase. In addition, in the case in which an opened/closed state of the upper door 940 and the side door 950 is judged by the plurality of sensors, reliability of the sheet feeding apparatus falls.